public class ChangeCalculator {
    public static void main(String[] args) {
        double originalAmount = 2.0;
        double expense = 1.1;
        double change = calculateChange(originalAmount, expense);
        System.out.println("找零为：" + change);
    }

    public static double calculateChange(double original, double expense) {
        return original - expense;
    }
}   